Motion-compensated light-emitting apparatus

ABSTRACT

A light-emitting apparatus, for enabling a beam of light to be projected on a desired target located a distance away to project the beam on the desired target without any or substantially any undesired movement. The apparatus may include a housing, a light generating device located within the housing and operable to generate a beam of light, a sensing device or devices for sensing an undesired action of the housing, a control circuit operable to provide a control signal corresponding to the sensed undesired action, and a drive device operable to counter act all or at least some of the undesired action of said housing in accordance with said control signal. The sensing device or devices may be one or more gyroscopes, accelerometers or other such devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/043,852, filed Mar. 6, 2008, entitled “Motion-CompensatedLight-Emitting Apparatus” which in turn is a continuation-in-part ofU.S. patent application Ser. No. 11/315,906, filed Dec. 22, 2005,entitled Motion-Compensating Light Emitting Apparatus, which in turn isa continuation-in-part of U.S. patent application Ser. No. 11/022,215,now U.S. Pat. No. 7,312,863, filed Dec. 23, 2004, entitledMotion-Compensating Light-Emitting Apparatus, all of which areincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to a system for maintaining abeam of electromagnetic radiation, such as visible light, pointed in aparticular direction, despite unwanted movement of the device emittingthe beam with respect to an inertial frame of reference.

BACKGROUND OF THE INVENTION

The present invention relates to light-emitting devices and particularlyto those devices intended to produce a beam in a selected direction suchas toward a target of interest. The invention providesmotion-compensation technology suitable for use with such light-emittingdevices, which may dampen and/or substantially eliminate the effect ofunintentional motion, vibration, or movements, such as angular and/ortranslational movements, caused by mechanical vibrations, hand tremors,and so forth.

Light-emitting devices, such as laser diode devices, are used in avariety of consumer, computer, business, medical, scientific, military,outdoor, telecommunication and industrial products, including but notlimited to compact disk (CD) players and computer CD-ROM drives, digitalvideo disk (DVD) players and DVD-ROM drives, laser printers, laserpointers, barcode scanners, measurement devices, rangefinders, scopes,industrial material processing devices, marking and cutting systems,medical equipment, fiber optic transmission systems, satellitecommunications, and digital printing presses. Many of these applicationsrequire precision accuracy for successful implementation. However,conventional light-emitting devices may be affected by unintentionalangular and/or translational movements (e.g., fine vibrations from themachine in which a laser is encased, fine tremors from a shaking handholding a laser, etc.) and, as a result, generate an unsteady column oflight—producing an effect that may cause inferior performance.

An example of the above mentioned effect will now be described withreference to a laser pointer. Fine tremors of the human hand, whenholding even a lightweight laser pointer (or other pointing device),have been measured at a frequency range of 1 to 5 Hz. These unwantedvibrations are often amplified when the person maneuvering the device isnervous. The resulting deviation of the projected spot from the intendedtarget point to the actual point is proportional to the distance fromthe pointing device to the target object (e.g., a point on a screen).This deviation may be approximately equal to the product of the sine orthe tangent of the angle and the distance to the projected spot. Inother words, for small angular movements (such as less than 10 degrees),the movement of the projected spot is approximately equal to the productof the distance to the target and the angle of the movement (inradians). For instance, small angular movements of +/−1 degree of alaser pointing device may result in movements of approximately +/−2 cmof the projected spot on a target 1 meter away; and, these angularmovements will result in a 10-fold larger projected spot movement(approximately +/−20 cm) for a target 10 meters away (which may betypical of large lecture halls). In contrast to angular movements,translational movements (sideways movements of the hand) are notamplified by the distance from the light-emitting device to the targetobject. That is, if the hand holding a laser pointer is moved sidewaysby 1 cm, the spot on the target is also moved sideways by 1 cmirrespective of how far the target is from the hand.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a motion-compensated, light-emittingapparatus which enables a steady beam of light to be projected onto adesired target even if subjected to undesired unsteady conditions byautomatically redirecting or compensating for unintentional, off-targetangular and/or translational movements. The present apparatus may useminiature gyroscopes and/or accelerometers and/or other motion sensingtype devices and an optical system including light-refracting elementsarranged within the apparatus. In a preferred embodiment of the presentinvention, a motion-compensating light-emitting device is provided whichutilizes a mirror mounted on a cantilever composed of an aluminum andLead Zirconium Titanate (PZT) metal sandwich. In a preferred embodiment,the mirror, positioned by the cantilever, deflects the light beam tocompensate for the unwanted tremor based on the angular rates and/ortranslational motion measured by two or more motion sensors.

In an alternate embodiment of the present invention, amotion-compensated, light-emitting device utilizes a micro mirror in atwo axis Micro-Electronic Mechanical System (MEMS)-based, gimbal-lessscanning mirror device. In a preferred embodiment, a commerciallyavailable MEMS, made entirely of monolithic single-crystal silicon in asingle miniature package, changes a mirror angle in two deflection axes.When an electric field is applied to the preferred two axis MEMS, themirror surface tilts an amount that is proportional to the appliedvoltage to stabilize the direction of the emitted light beam.

In an alternate embodiment of the present invention a motioncompensated, light-emitting device is provided that displays a varietyof stabilized-rasterized and stabilized-vector graphics as well asstabilized multi-frame animations at arbitrary refresh rates. The systemis highly adaptable to projection onto various surfaces and in a varietyof applications, including projection onto specially-coated transparentsurfaces. Due to the low power consumption and vibration stabilizedoutput of this device, the system preferably is miniaturized, highlyportable and fully mobile when used with a laptop small computer. Thecomputer may project different letters, symbols, or graphics or otherstatic or moving images that can change and evolve over time. The systempreferably includes a two axis MEMS micro mirror. The signals providingthe desired rasterized or vector graphics are added to the vibrationstabilization signals, and unwanted movement is reduced or eliminated inthe resulting projection.

In an alternate embodiment of the present invention, amotion-compensated, light-emitting device displays full color,high-quality images that remain in focus at all distances usingholographic laser projection technology. The term “holographic” refersnot to the projected image, but to the method of projection. Adiffraction pattern of the desired 2D image, calculated usingholographic algorithms, is displayed on a phase-modulating LiquidCrystal on Silicon (LCOS) microdisplay attached to a two axis MEMS micromirror. When illuminated by coherent laser light, the desired image isprojected on various surfaces without distortion by the micro-tremorsimposed on the projection system.

Rather than blocking light, a phase-modulating LCOS microdisplay mountedon the MEMS micro mirror steers light to exactly where it is needed,making the system highly efficient. Unlike conventional projectionsystems, a projection lens is not needed. Instead, a demagnificationlens pair expands the diffracted image from the microdisplay, producingan ultra-wide throw angle, greater than 100°. The projected images arein focus at all distances from the projector, eliminating the need forfocus control.

The diffractive method of projection naturally lends itself tominiaturization and low cost implementation, allowing images to beprojected onto curved and angled surfaces without distortion. Inaddition, the system is highly tolerant of microdisplay pixelfailure—essential in safety critical applications in markets such asautomotive.

In an alternate embodiment of the present invention amotion-compensated, light-emitting device stores the exact orientationof the laser or projection system for later retrieval, derived from alocation determination system, a range to target determination systemand information from motion detection devices such as accelerometersunder user control. The system automatically maintains a light beamemitted from the device in the exact orientation, as stored. Inaddition, the system may store several orientations, and the system canreorient the light beam in sequential, round-robin fashion. Withsufficient displacement of the compensating mirrors, the system can bemoved from its location, and if the targets are far enough away, thesystem can maintain the orientation of the light beam at the markedtargets. In addition, by adding some simple modulation to the laserlight beams the beams can be turned off when not actually pointing atmemorized locations, thus maintaining illumination only at the desiredlocations that were previously set in memory.

In one aspect, the present invention is directed to a light-emittingapparatus comprising: a light beam generator that emits a light beam; adevice that produces a first signal indicating motion of the generator;an integrator that integrates the first signal to produce a secondsignal indicating movement of the light beam generator; and a lightdiverting device mounted to an electronically adjustable cantilever;wherein the second signal is applied to the cantilever so that the lightbeam projects substantially in a particular direction.

In another aspect of the present invention, the cantilever comprises afirst layer of ceramic and a second layer of lead zirconium titanate.

In another aspect of the present invention, the apparatus furthercomprises first and second angular rate-sensing devices; and first andsecond cantilevers; wherein the first angular rate-sensing devicemeasures pitch angular velocity and the second angular rate-sensingdevice measures yaw angular velocity, the integrator integrates signalsproduced by both first and second signals and the integrated signals areapplied to the first and second cantilevers, respectively.

In another aspect of the present invention, the apparatus furthercomprises a graphics generator that generates a third signal; and asignal combiner that combines the first and second signals with thethird signal; wherein the third signal, applied to the cantilevers,diverts the light beam to project an image.

In another aspect of the present invention, the apparatus furthercomprises a user interface that selects a current orientation of thegenerator; and a memory that stores the current orientation; wherein theapparatus maintains the light beam projected at the current orientation.

In another aspect of the present invention, the apparatus furthercomprises a measurement device that generates a third signalrepresentative of a measured orientation and wherein the memory furtherstores the measured orientation.

In another aspect of the present invention, the measurement devicecomprises a digital magnetometer and the measured orientation isazimuth.

In another aspect of the present invention, the memory stores more thanone orientation and the apparatus directs the beam in a sequence of oneor more directions from the orientations stored in the memory.

In another aspect of the present invention, the light diverting devicecomprises a mirror.

In another aspect of the present invention, the light diverting devicecomprises a lens.

In another aspect of the present invention, the integrator integratesthe first signal to produce a second signal that indicates an angularand translational movement of the light beam generator; and; wherein thesecond signal is applied to the cantilever so that angular andtranslational movement is substantially eliminated.

In another aspect, the present invention is directed to a light-emittingapparatus comprising: a light beam generator that emits a light beam; amotion-sensing device that produces a first signal indicating movementof the generator; an integrator that integrates the first signal toproduce a second signal indicating a movement of the light beamgenerator; and a micro electronic mechanical system that positions alight diverting device; wherein the second signal is applied to themicro electronic mechanical system to project the beam substantially ina particular direction.

In another aspect of the present invention, the light diverting devicecomprises a mirror.

In another aspect of the present invention, the light diverting devicecomprises a lens.

In another aspect of the present invention, the apparatus furthercomprises first and second angular rate-sensing devices; wherein thefirst angular rate-sensing device measures pitch angular velocity andthe second angular rate-sensing device measures yaw angular velocity,the integrator integrates signals produced by both first and secondsignals and the integrated signals are applied to the micro electronicmechanical system.

In another aspect of the present invention, the apparatus furthercomprises a graphics generator that generates a third signal; and asignal combiner that combines the first and second signals with thethird signal; wherein the third signal, applied to the micro electronicmechanical system, diverts the light beam to project an image.

In another aspect of the present invention, the integrator integratesthe first signal to produce a second signal that indicates an angularand translational movement of the light beam generator; and; wherein thesecond signal is applied to the micro electronic mechanical system toproject the beam so that angular and translational movement issubstantially eliminated.

In another aspect of the present invention, the apparatus furthercomprises a user interface that selects a current orientation of thegenerator; and a memory that stores the current orientation; wherein theapparatus maintains the light beam projected at the current orientation.

In another aspect of the present invention, the apparatus furthercomprises a measurement device that generates a third signalrepresentative of a measured orientation and wherein the memory furtherstores the measured orientation.

In another aspect of the present invention, the measurement devicecomprises a digital magnetometer and the measured orientation isazimuth.

In another aspect of the present invention, the memory stores more thanone orientation and the apparatus directs the beam in a sequence of oneor more directions from the orientations stored in the memory.

In another aspect of the present invention, the apparatus furthercomprises a plurality of colored lasers; and a laser collimating devicethat combines the plurality of colored lasers into a single beam;wherein the light beam generator comprises the plurality of coloredlasers; and wherein the light diverting device comprises a micro displaythat generates an image from the single beam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a motion-compensating light-emitting apparatusaccording to an embodiment of the present invention;

FIG. 2 is a diagram of the motion-compensating light-emitting apparatusof FIG. 1 to which reference will be made in explaining the operationthereof;

FIG. 3 is a diagram of a motion-compensating light-emitting apparatusaccording to another embodiment of the present invention;

FIG. 4 is a diagram of the motion-compensating light-emitting apparatusof FIG. 3 to which reference will be made in explaining the operationthereof;

FIG. 5 is a diagram to which reference will be made in explaining theoperation of the present apparatus;

FIG. 6 is a diagram of a motion-compensating light-emitting apparatusaccording to another embodiment of the present invention;

FIG. 7 is a block diagram of a motion-compensated, laser diode pointerutilizing cantilevers;

FIG. 8 is a block diagram of a motion-compensated light-emittingapparatus according to another embodiment of the present inventioncomprising a two axis MEMS based micro mirror;

FIG. 9 is a block diagram illustrating a motion-compensatedlight-emitting device for displaying a variety of stabilized rasterizedand stabilized vector graphics as well as stabilized multi-frameanimations at arbitrary refresh rates;

FIG. 10 is a block diagram of a motion-compensated, holographic laserprojector; and

FIG. 11 is a block diagram of a motion and position compensated laserpointer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a diagram of a laser diode pointer 100 which includesvibration or motion compensation circuitry in accordance with anembodiment of the invention. A visible laser diode 110 may be used asthe light source. There are several ways of implementing the vibrationcompensation scheme. In accordance with an embodiment of the invention,two angular velocity sensors (gyros) 120 and 125 are aligned inorthogonal directions and used to measure the angular movements in thepitch and yaw axis (also referred to as the X and Y axis). In apreferred embodiment, the two miniature gyroscopes comprise, forexample, a micro electro mechanical system (“MEMS”), such as modelADXRS150 manufactured by Analog Devices, Inc. These gyros may have arelatively small volume (such as less than 0.15 cm³), low weight (suchas less than 500 mg), and small size (such as 7 mm×7 mm×3 mm or less).In another embodiment of the present invention, a motion-compensatinglight-emitting device is provided which utilizes two or three miniatureaccelerometers (for example, MEMS, such as model ADXL203 manufactured byAnalog Devices, Inc.) arranged to measure acceleration and changes ofthe gravity vector (changes in acceleration) or relative tilts withrespect to the vertical axis in two orthogonal directions (i.e., yaw andpitch) and to obtain from this information the relative vertical andhorizontal angular movements and translational movements. Theseaccelerometers may have a relatively small volume 0.05 cm³ (withdimensions of 0.5 cm×0.5 cm×0.2 cm). Additionally, the accelerometersmay be provided in a hermetically sealed package.

The output of gyros 120 and 125 are amplified by two amplifiers 131 and132 respectively and/or sampled by an A/D converter 133 inanti-vibration control circuit 130. The sampled signal may be passed toa band frequency filter 134 where the portion of the signal associatedwith the rapid, unwanted angular motions of the pointer in this example,typically that portion between 1 and 5 Hz, is extracted. Although a bandfrequency filter having a range of 1 to 5 Hz is described, a variablefrequency filter may be used to set the desired band of frequencies. Therange of frequencies may be adjusted by utilizing an adjustment typedevice such as a variable resistor or digital switches.

The filtered signal may then be integrated by an integrating processorcircuit 135. Because gyros 120 and 125 measure angular velocity, thesignal received by integrating processor circuit 135 may be integratedto obtain angular information from which an angular difference may beobtained. Although the embodiment of FIG. 1 utilizes gyros 120 and 125that measure angular velocity, gyros 120 and 125 may measure an angulardifference. In such instance, integrating processor circuit 135 may notbe included in the anti-vibration control circuit 130.

The integrated rate output or angular difference (proportional to theangle of the unwanted angular motion) may be conditioned by a correctionamount normalization circuit 136 (which may include amplifying thesignal by a necessary or predetermined amount) and supplied as an inputfor motors 140 and 150, which may be connected to a movable lens 160(which may be located between the laser diode 110 and a focusing lens170). Movable lens 160 and focusing lens 170 may each be constructedfrom one or more convex lenses and/or concave lenses, or a combinationof convex and concave lenses, or one or more convex/concave type lenses,or any combination thereof. The signals may be conditioned so that thefeedback loops provide an input signal to the motion correctionmechanisms such that the resulting circuits are stable in the region ofinterest. The conditioning may include adjusting the gain of the signalas well as adjusting for the null of the circuit and the zero offset ofthe gyros. Thus, if the integrated rate output measured is equal to 1degree, the amplified signal has to equal a voltage (or current) thatwill produce a motor movement required to move the compensating lens fora one degree of motion.

The anti-vibration control circuit 130 may be part of a microprocessoror microcomputer, or could be constructed out of individual analog anddigital elements depending on the cost, size and power consumption ofeach implementation. Additionally, an on/off switch may be provided inlaser diode pointer 100 which may enable a user to turn off theanti-vibration control circuit if the user does not want to use themotion compensating function.

FIG. 2 is a diagram of a laser diode pointer 100 when it is tilted down.The gyros 120 and 125 may measure the angular velocity of the tilt, andtheir output signals (which may be in analog form) are proportional tothe angular rate of the motion. Such signals may then be amplified,digitized and passed to the band pass frequency filter 134. The bandfrequency filter 134 may extract the portion of the signal(s) associatedwith rapid unwanted angular motion (e.g. unwanted hand tremors which maybe in the 1 to 5 Hz range). The filtered signal may then be integratedby the integrating processor circuit 135. The normalizing andconditioning circuit 136 may receive the integrated signal and, inaccordance therewith, may generate a voltage or current signal having avalue or magnitude corresponding to the necessary compensation, and maycause the same to be supplied to compensating element(s) (such as motors140 and 150). In response thereto, the motors 140 and 150 may cause thecorrective lens 160 to move in a direction such that an exiting beamcontinues to exit the laser pointer 100 in a horizontal or asubstantially horizontal direction. Without the movement of thiscorrective movable lens 160 the beam would exit at a downward angle. Themotors 140 and 150 may be an electro-motor, an electromagnetic motor, apiezo-electric motor or any other type of actuator suited for thisapplication.

Although not shown in this diagram, laser pointer 100 (which includesthe gyros and the anti-vibration circuit) may be powered by a powersource such as two 1.5V batteries connected in series as used forordinary laser pointers. To save on power usage, the motion-compensationtechnology may be activated only upon activation of the laser pointer.

Although FIG. 2 depicts a laser diode pointer 100 tilted on one axis andits resulting compensation, tilting on the other axis would becompensated similarly (and independently) and is not illustrated inorder to keep the drawings simple and easy to follow.

In another embodiment of the invention, and as shown in FIG. 3, a laserdiode pointer 200 may use a movable bellows 210 that may be filled witha high refractive index solution or material 220 instead of correctivemovable lens 160. The refractive index of the high refractive indexsolution or material 220 may be approximately 1.33 or higher. The highrefractive index solution or material 220 may be stored between twosheets of glass 230 and 240 such that the portion of the high refractiveindex solution in the path of the optical beam may be adjusted (bysqueezing or spreading the bellows) based on the angular rates measuredby the two angular velocity sensors or gyros 120 and 125. Instead ofmoving an optical lens to change the direction of the exiting beam thebellows filled with high refractive index solution may be contracted onone end and expanded on the other end so as to bend the exiting lightbeam in a direction opposite to the unwanted motion.

FIG. 4 shows how such a change in the thickness or arrangement of thebellows may cause the beam to bend so as to compensate for the unwantedmotion. As in the previously described laser pointer having a movablelens, the laser pointer 200 may be powered by a power source such as anumber of batteries arranged in a predetermined manner. Additionally,FIGS. 3 and 4 indicate how motion in the pitch or X axis is compensated;however, motion in the yaw or Y axis may be compensated similarly (andindependently) and is not illustrated in order to keep the drawingssimple and easy to follow.

FIG. 5 is a flow chart describing how a laser pointer in accordance withan embodiment of the present invention compensates for unwanted motion.The process starts in step S100 where the laser pointer is turned on bypressing a button or the like. During operation of the laser pointer, asensing means, which may include gyros or accelerometers or acombination thereof, measure movement and output a signal which may beprocessed by the anti-vibration control circuit. Such processing mayinclude the analog to digital conversion performed by the A/D converter133. Processing may then proceed to step S120 wherein the signal may besupplied through a band pass filter so as to effectively detect andextract signals corresponding to the unwanted motion of the laserpointer (unwanted motion may be in the 1 to 5 Hz range). If the sensingmeans does not detect unwanted motion, the method may proceed to stepS130 where the correcting lens or bellows is not moved and the beamexits the laser pointer with out any redirection. If there is unwantedmotion detected by the sensing means, the method proceeds to step S140where the processed signal may be integrated and/or amplified. A voltageor current corresponding to the processed and/or amplified signal may beapplied to the drive motors in step S150, which in turn, may move theprism or the bellows in step S160. In step S170, the beam may beredirected in the direction opposite the direction of the hand tremor.

FIG. 6 is a diagram of another embodiment of the laser diode pointer 300wherein accelerometers are utilized instead of gyroscopes. Three angularvelocity and/or translational motion sensors (accelerometers) 310, 320,and 330, which may be aligned in orthogonal directions, may be used tomeasure the angular and/or translational movements in the pitch, yaw androll axis (also referred to as the X, Y and Z axis) respectively. Theoutput of accelerometers 310, 320, and 330 may be respectively amplifiedby three amplifiers 340, 350, and 360, and then sampled by A/D converter133 in the anti-vibration control circuit 330. The portion of the signalassociated with rapid unwanted angular and/or translational motions ofthe pointer (e.g., an unwanted hand tremor in the 1-5 Hz range) may beextracted by band pass filter 134 and integrated by integratingprocessor circuit 135. Movements (tilts) of the laser pointer may bemeasured by comparing the measured acceleration to a gravity vector (gacceleration) as the laser pointer is tilting and/or computing themotions from the three orthogonal measurements of the acceleration.

The computed integrated rate output (proportional to the angle of theunwanted angular and/or translational motion) may be conditioned (whichmay include amplifying the signal by a necessary or predeterminedamount) and/or used as the input for motor(s) that may be coupled tomovable lens 160 located between the laser diode 110 and the focusinglens 170. The anti-vibration circuit 330 may be included in amicroprocessor or microcomputer or may be constructed out of individualanalog and/or digital elements depending on the cost, size and powerconsumption requirements.

FIG. 7 is a block diagram of another embodiment of the presentinvention. A motion-compensated, laser diode pointer illustrated in FIG.7 comprises a laser emitting diode 110, motion sensors 120, 125, signalamplifiers 131, 132, an A/D converter 133, high pass filter 134,integrating circuit 135, normalization circuit 136, pitch drive 140, yawdrive 150, and mirrors 310 and 320 mounted on cantilevers 350 and 360.Preferably, Bimorph ceramic cantilever strips 350 and 360 comprise LeadZirconium Titanate (PZT)—metal sandwich strips, or other piezoelectricmaterials. Cantilevers 350, 360 may be composed of single or multipleelements. Mirrors 310, 320 may be moved by various other means inaddition to bimorph ceramic strips of the type used for thisapplication.

In operation, the function of laser emitting diode 110, motion sensors120, 125, signal amplifiers 131, 132, an A/D converter 133, high passfilter 134, integrating circuit 135, normalization circuit 136, pitchdrive 140 and yaw drive 150 are described above and will not be repeatedhere. Voltage generated by these components are applied to cantilevers350, 360, causing them to bend and thus to change the angle of mountedmirrors 310, 320. The voltage applied to cantilevers 350, 360 deflectseach cantilever proportional to the magnitude of the voltage applied.Mirrors 310 and 320 at the end of cantilevers 350, 360 deflect the laserbeam. A mirror deflection of one degree of angle will deflect light by atwo degree of angle deflection—one degree of deflection for the incidentbeam and one degree of deflection for the reflected beam. Thus, moving amirror is twice as efficient as moving a lens. The amount of deflectionmay be adjusted based on the angular rates measured by the two motionsensors 120 and 125. Preferably, motion sensors 120, 125 are angularvelocity sensors or gyros.

In an alternate embodiment (not illustrated), a set of three to sixaccelerometers are connected to the body of the laser pointer to measurethe unwanted vibrations by measuring the changes of the gravity vectorduring the unwanted vibration of the laser pointer. Three accelerometerswould be the minimum number required and six accelerometers wouldprovide additional accuracy for determining the amount of unwantedvibration present.

FIG. 8 is a block diagram of a motion-compensated light-emittingapparatus according to another embodiment of the present inventioncomprising a two axis MEMS based micro mirror. As illustrated in FIG. 8,the system includes a two axis MEMS micro mirror 410, in addition to theaforementioned components laser emitting diode 110, motion sensors 120,125, signal amplifiers 131, 132, an A/D converter 133, high pass filter134, integrating circuit 135, normalization circuit 136, pitch drive140, yaw drive 150. Two axis MEMS micro mirror 410 is preferably acommercially available unit, such as from Mirrorcle Technologies Inc.,type SO308. The mirror changes angle with respect to the package in asimilar manner as large scale galvanometer based optical scanners,except that MEMS micro mirror 410 requires several orders of magnitudeless driving power. In addition, micro mirrors devices that change inboth deflection axes are readily available in a single miniature devicethat is very compact, typically smaller than 8 mm×14 mm×2 mm.

In operation, the function of laser emitting diode 110, motion sensors120, 125, signal amplifiers 131, 132, an A/D converter 133, high passfilter 134, integrating circuit 135, normalization circuit 136, pitchdrive 140 and yaw drive 150 are described above and will not be repeatedhere. In this embodiment, the angle of mirror 410 can be controlledindependently in each of two axes (X and Y) by the applied voltage fromindependent mirror drives 140 and 150. Mirror 410 will deflect the beamproportional to the applied voltage in each axis. The amount ofdeflection may be adjusted based on the angular rates measured by themotion sensors 120 and 125. A voltage applied to the MEMS micro mirrortilts to change the angle of mirror 410. As described above, moving amirror is twice as efficient as moving a lens. Thus, with a mirrordeflection of one degree of angle, the light is deflected twodegrees—one degree of deflection for the incident beam and one degree ofdeflection for the reflected beam.

In an alternate embodiment (not illustrated), a set of three to sixaccelerometers are connected to the body of the laser pointer to measurethe unwanted vibrations by measuring the changes of the gravity vectorduring the unwanted vibration of the laser pointer. Three accelerometerswould be the minimum number required and six accelerometers wouldprovide additional accuracy for determining the amount of unwantedvibration present.

FIG. 9 is a block diagram illustrating a motion-compensatedlight-emitting device for displaying a variety of stabilized rasterizedand stabilized vector graphics as well as stabilized multi-frameanimations at arbitrary refresh rates. As illustrated in FIG. 9, thesystem comprises laser emitting diode 110, motion sensors 120, 125,signal amplifiers 131, 132, an A/D converter 133, high pass filter 134,integrating circuit 135, normalization circuit 136, pitch drive 140, yawdrive 150 and a two axis MEMS micro mirror 410, all of which aredescribed above. In addition, the system comprises a signal conditioningfiltering and voltage control device 420, a computer or microprocessor430, a self contained vector graphics or raster graphics generator 440,a signal conditioning, filtering and voltage control unit 450 and avoltage adder 460, which are used to generate a projected image 470, forexample, a symbol, letter, or figure.

Image 470 is represented by a low level signal that is transmitted to asignal conditioning, filtering and voltage control device 420 bycomputer 430. Device 420 sends its output signal to a voltage adder 460that combines this output signal with the motion compensation signalfrom normalization circuit 136, to stabilize the projection of image470. In another embodiment, a self contained vector graphics or rastergraphics generator 440 can be self contained within the proposed laserpointer system. The signal output of generator 440 is sent to a signalconditioning, filtering and voltage control unit 450 to ensure theproper dimensioning of the projected image 470. Signal conditioning,filtering, voltage control system 450 sends an output signal to thevoltage adder/combiner 460. After the voltages for the vibrationstabilization 136 and the generation of the image 470 have beencombined, the signals are provided as input to the respective X and Yaxis mirror drive units 140 and 150. By superposition, the resultingsystem projects the desired rasterised or vector graphic with the motionreduction signal in a manner that would not be possible without thevibration stabilization portion as often the resulting projection wouldbe unrecognizable or unreadable because of laser beam jitter.

The system is highly adaptable to projection onto various surfaces andin a variety of applications, including projection onto specially-coatedtransparent surfaces. Due to the low power consumption and vibrationstabilized output of this device, the system is highly portable,especially mobile when used with a laptop small computer. A computer canbe used for a generator 440 to project different letters, symbols, orgraphics or other static or moving images 470 that can change and evolveover time as well as be a function of the material that is presented.

In an alternate embodiment (not illustrated), a set of three to sixaccelerometers are connected to the body of the laser pointer to measurethe unwanted vibrations by measuring the changes of the gravity vectorduring the unwanted vibration of the laser pointer. Three accelerometerswould be the minimum number required and six accelerometers wouldprovide additional accuracy for determining the amount of unwantedvibration present.

FIG. 10 is a block diagram of a motion-compensated, holographic laserprojector. As illustrated in FIG. 10, a motion-compensated projectiondevice is provided comprising motion sensors 120, 125, signal amplifiers131, 132, an A/D converter 133, high pass filter 134, integratingcircuit 135, normalization circuit 136, pitch drive 140, yaw drive 150and a two axis MEMS micro mirror 410, all of which are described above.In addition, the system comprises lasers 500, collimating lenses 510,mirrors 520, demagnification lenses 530, projected display 540 and microdisplay 550.

The motion-compensated projection device displays full color,high-quality images that remain in focus at all distances usingholographic laser projection technology. The term “holographic” refersnot to the projected image, but to the method of projection. Threelasers of magenta, blue and green color 500 each generate a laser beamthat is collimated by individual lenses 510. The beams are reflected andcombined into a single beam by three mirrors 520. The combined beam isthen reflected off micro display 550. A diffraction pattern of thedesired 2D image, calculated using holographic algorithms, is displayedon this phase-modulating Liquid Crystal on Silicon (LCOS) micro display550 that is attached on top of a two axis MEMS micro minor 410. Whenilluminated by coherent laser light, the desired image 540 is projectedon various surfaces without being distorted by the micro-tremors of theprojection system.

Rather than blocking light, the phase-modulating LCOS micro display 550mounted on MEMS micro minor 410 steers the light to exactly where it isneeded, making the system highly efficient. By combining the holographiclaser projection technology with the vibration reduction technique aprojection system is created that projects images without alsoprojecting the various vibrations and tremors of the projection systemor the support structure of the projection system. The resulting systemprojects the desired image in a manner that would not be possiblewithout the vibration stabilization portion as often the resultingprojection would be of much lower quality, unrecognizable or unreadablebecause of laser beam jitter, or jitter in all elements used to projectthe image on the desired surface.

Unlike conventional projection systems, this type of technology does notrequire a projection lens. Instead, a demagnification lens pair expandsthe diffracted image from the micro display, producing an ultra-widethrow angle greater than 100°. The projected images are in focus at alldistances from the projector, eliminating the need for a focus control.The diffractive method of projection naturally lends itself tominiaturization and low cost implementation. It allows images to beprojected onto curved and angled surfaces without distortion, and ishighly tolerant to micro display pixel failure—essential in safetycritical applications in markets such as automotive.

In an alternate embodiment (not illustrated), a set of three to sixaccelerometers are connected to the body of the laser pointer to measurethe unwanted vibrations by measuring the changes of the gravity vectorduring the unwanted vibration of the laser pointer. Three accelerometerswould be the minimum number required and six accelerometers wouldprovide additional accuracy for determining the amount of unwantedvibration present.

FIG. 11 is a block diagram of a motion and position compensated laserpointer. As illustrated in FIG. 11, the system comprises laser emittingdiode 110, signal amplifiers 131, 132, an A/D converter 133, high passfilter 134, integrating circuit 135, normalization circuit 136, pitchdrive 140, yaw drive 150 and a two axis MEMS micro mirror 410, all ofwhich are described above. In a preferred embodiment, the system furthercomprises a memory 560, a computer 570, X and Y accelerometers 580 and590, a digital magnetometer 595, a location indicator 596 and a rangeindicator 597.

The motion-compensated projection device stores in memory 560 theorientation of the laser or projection system at times directed by theuser. For example, the user may mark a target by pressing a button (notshown). Signals from two angular position and/or translational motionsensors or accelerometers, in the X and Y orientation 580 and 590 and adigital magnetometer 595 (for azimuth orientation) indicate theorientation of the laser pointer when the user so indicates. Inaddition, location indicator 596 and range indicator 597 provideposition and range to target information that is stored in memory 560for later retrieval. Memory 560 is accessed by computer 570. In analternative method of operation, the desired positions could bedownloaded from computer 570 into memory 560. The system maintains thelaser pointed in the marked orientation. In addition, several points canbe marked in sequence, and the laser can scan and point at them in around-robin fashion.

In an alternate embodiment (not illustrated), a set of three to sixaccelerometers are connected to the body of the laser pointer to measurethe unwanted vibrations by measuring the changes of the gravity vectorduring the unwanted vibration of the laser pointer. Three accelerometerswould be the minimum number required and six accelerometers wouldprovide additional accuracy for determining the amount of unwantedvibration present.

Having thus described at least illustrative embodiments of theinvention, various modifications and improvements will readily occur tothose skilled in the art and are intended to be within the scope of theinvention. Accordingly, the foregoing description is by way of exampleonly and is not intended as limiting.

Although the above embodiments describe laser pointers that may utilizespecific combinations of gyroscopes or accelerometers, the presentinvention is not so limited. For example, the present invention may alsoutilize other types of motion sensing devices or may utilize a differentnumber of gyroscopes or accelerometers or may utilize a combination ofgyroscopes and accelerometers to sense unwanted motion. In addition,although a “light beam” is recited, the invention shall not be limitedto a ray of visible light, but shall also encompass other forms ofelectromagnetic radiation that can be reflected or refracted, as is wellknown in the art, such as infrared, ultraviolet, or even x-ray or othernon-visible radiation. Although preferred embodiments of the presentinvention and modifications thereof have been described in detailherein, it is to be understood that this invention is not limited tothose precise embodiments and modifications, and that othermodifications and variations may be effected by one skilled in the artwithout departing from the spirit and scope of the invention as definedby the appended claims.

1. A light-emitting apparatus comprising: a light beam generator thatemits a light beam; a device that produces a first signal indicatingmotion of the generator; an integrator that integrates the first signalto produce a second signal indicating movement of the light beamgenerator; and a light diverting device mounted to an electronicallyadjustable cantilever; wherein the second signal is applied to thecantilever so that the light beam projects substantially in a particulardirection.
 2. The apparatus of claim 1, wherein the cantilever comprisesa first layer of ceramic and a second layer of lead zirconium titanate.3. The apparatus of claim 2, further comprising: first and secondangular rate-sensing devices; and first and second cantilevers; whereinthe first angular rate-sensing device measures pitch angular velocityand the second angular rate-sensing device measures yaw angularvelocity, the integrator integrates signals produced by both first andsecond signals and the integrated signals are applied to the first andsecond cantilevers, respectively.
 4. The apparatus of claim 3, furthercomprising: a graphics generator that generates a third signal; and asignal combiner that combines the first and second signals with thethird signal; wherein the third signal, applied to the cantilevers,diverts the light beam to project an image.
 5. The apparatus of claim 3,further comprising: a user interface that selects a current orientationof the generator; and a memory that stores the current orientation;wherein the apparatus maintains the light beam projected at the currentorientation.
 6. The apparatus of claim 5, further comprising ameasurement device that generates a third signal representative of ameasured orientation and wherein the memory further stores the measuredorientation.
 7. The apparatus of claim 6, wherein the measurement devicecomprises a digital magnetometer and the measured orientation isazimuth.
 8. The apparatus of claim 7, wherein the memory stores morethan one orientation and the apparatus directs the beam in a sequence ofone or more directions from the orientations stored in the memory. 9.The apparatus of claim 1, wherein the light diverting device comprises amirror.
 10. The apparatus of claim 1, wherein the light diverting devicecomprises a lens.
 11. The apparatus of claim 1, wherein the integratorintegrates the first signal to produce a second signal that indicates anangular and translational movement of the light beam generator; and;wherein the second signal is applied to the cantilever so that angularand translational movement is substantially eliminated.